Problem: If $5a + 5b + 3c = -7$ and $3x + 5y + 3z = -1$, what is $-20b - 27z - 27x - 45y - 20a - 12c$ ?
Solution: $= -20a - 20b - 12c - 27x - 45y - 27z$ $= (-4) \cdot (5a + 5b + 3c) + (-9) \cdot (3x + 5y + 3z)$ $= (-4) \cdot (-7) + (-9) \cdot (-1)$ $= 28 + 9$ $= 37$